Workers prepare the podium before the start of the BlackBerry 10 launch event by Research in Motion at Pier 36 in Manhattan on Jan. 30. / Mario Tama, Getty Images

by Scott Martin, USA TODAY

by Scott Martin, USA TODAY

SAN FRANCISCO -- Doubts emerged Wednesday as to whether Fairfax Financial's Prem Watsa could muster up the financial support needed to take troubled smartphone maker BlackBerry private in a $4.7 billion bid.

BlackBerry shares fell 6% by close of trading on concerns the company's deal to go private with Fairfax Financial won't survive.

"Chances of the deal going through appear grimmer at most," Bernstein Research analyst Pierre Ferragu said in a note to clients.

Shares of BlackBerry slid 53 cents, at $8.01, to close on the latest blow of bad news for the downward-spiraling smartphone maker.

BlackBerry on Monday announced plans to forge a deal to go private with a group of investors led by Fairfax, the insurance business run by Watsa. The move came after the company on Friday confirmed plans to slash its workforce by 4,500 and warned it expects a nearly $1 billion operating loss in the second quarter.

Troubled BlackBerry's deal to go private with Fairfax was touted prematurely because the company hasn't secured any type of other financing, notes Ferragu.

The deal for BlackBerry included $480 million from Fairfax, which won't be chipping in more financing to the deal. That would require $1 billion in equity injections and $3 billion in bank loans, prospects that appear "unrealistic," says Bernstein's researcher.

"We think it will be unlikely that enough other investors will be joining the bid that sounds like a last chance rescue attempt for Fairfax's stake," Ferragu said.